1. Field of the Invention
The invention relates to a device for applying tension to ground warp yams in a cloth movable type pile loom by the displacement of a ground warp tension roller.
2. Prior Art
A cloth movable type pile loom is provided with a terry motion mechanism. The terry motion mechanism moves a ground warp tension roller in the same direction as a woven cloth so as to move a cloth fell of a woven cloth back and forth. Accordingly, the terry motion mechanism is associated with a supporting mechanism of a ground warp tension roller to move the ground warp tension roller back and forth. The ground warp tension roller is naturally biased in the direction to apply tension to the ground warp yarns.
FIG. 1 shows a schematic view of a ground warp let-off tension device 1 of a conventional typical cloth movable type pile loom as disclosed in Japanese Patent Laid-Open Publication No. 9-111597. In FIG. 1, ground warp yarns 2 are unwound from a ground warp let-off beam 3, and they contact a ground warp tension roller 4, then they form a shedding 8 by a vertical movement of heddles 5, and finally they reach a cloth fell 7 of a woven cloth 6. Meanwhile, pile warp yarns 9 are unwound from a pile warp let-off beam 10 and contact a pile warp tension roller 11, then they reach the cloth fell 7 of the woven cloth 6. A weft yarn 12 inserted in the position of the shedding 8 is beaten up against the cloth fell 7 by a reed 13 to form the woven cloth 6, then the woven cloth 6 passes through a cloth moving roller 14 and is wound around a cloth winding roller 15.
Since both the cloth moving roller 14 and ground warp tension roller 4 move the woven cloth 6 and ground warp yarns 2 back and forth, they are supported by the terry motion mechanism 16 and a mechanism interlocked therewith. In this example, the terry motion mechanism 16 comprises brackets 18, 19 respectively attached to the right and left frames 17, L-shaped terry motion levers 20, 21 respectively rotatably supported by shafts 23, 24 relative to the brackets 18, 19, and links 22, and shafts 25, 26 for connecting the end portions of the terry motion levers 20, 21.
The terry motion levers 20 are biased clockwise by extension springs 27, and they are supported by a cam 28 and a cam roller 30 that contacts the outer periphery of a cam 28 so as to swing back and forth in synchronization with the rotation of a main shaft 32 of the loom. Meanwhile, the cam 28 is integrated with a camshaft 29 and is driven while interlocked with the rotation of the main shaft 32 of the loom. The cam roller 30 is rotatably supported by the roller shaft 31 of the terry motion levers 20.
The swingable motion of the terry motion levers 20 is transmitted to each one end of a pair of right and left swing levers 36 by way of a shaft 34, interlocking links 33 and a shaft 35. The swing levers 36 are swingably supported by a bracket 37 and a shaft 38 respectively fixed to the frames 17, and they swingably support a pair of right and left levers 41 by an intermediate shaft 39.
The pair of right and left levers 41 are connected to and integrated with each other by a roller shaft 40 serving as a shaft fully extending to the right and left thereof (hereinafter referred to as simply the through shaft) whereby the ground warp tension roller 4 is rotatably supported by the levers 41 at respective first ends while they are biased by an extension spring 42 in the direction to apply tension to the ground warp yarns 2 by way of the ground warp tension roller 4 at respective second ends. When the pair of right and left levers 41 are connected to and integrated with each other, a biasing force of the extension spring 42 acts on the right and left sides of the ground warp tension roller 4 uniformly to the right and left so as to apply a uniform tension to the ground warp yarns 2.
During the weaving operation, the cam 28 is synchronized with the rotation of the main shaft 32 to swing the terry motion levers 20 back and forth. Accordingly, respective terry motion levers 20 move the cloth moving roller 14 back and forth by way of respective links 22 and levers 21 while they move the ground warp tension roller 4 back and forth by way of the respective interlocking links 33 and swing levers 36. As a result, when the ground warp yarns 2 and woven cloth 6 are moved back and forth, the cloth fell 7 is set to a first pick position and a loose pick position corresponding to the weaving texture.
Meanwhile, as looms have lately been operating at higher speeds and becoming large in width, the looms are required to increase in rigidity, so that respective components of the loom become heavy, Accordingly, a load applied to the terry motion mechanism 16 increases so that a breakage in the terry motion 16 mechanism occurs. Further, since the extension spring 42 is repeatedly moved back and forth when the device is moved back and forth, a desired elasticity is not obtained due to the fatigue of the extension spring 42 so that the extension spring 42 has become broken at an early stage. Since the roller shaft 40 of the ground warp tension roller 4 is a through shaft for connecting and integrating the pair of right and left levers 41 with each other, it is heavy so that inertia of the ground warp tension roller 4 becomes large. Accordingly, it is difficult for the ground warp tension roller 4 to move quickly to follow the change of tension of the ground warp yarns 2 so that the tension is kept constant.